1. Field of the Invention
The preset invention relates to an inverter device that detects an inverter output voltage and detects a motor residual voltage or its phase.
2. Discussion of the Background
There is an inverter device described in Japanese Laid-open Patent Publication No. 6-121544. The inverter device consists of a voltage dividing circuit for dividing a DC voltage Vdc by half, a diode bridge that is connected in anti-parallel with a detection power source (drive power source) in which two DC power sources are connected in series, an output voltage of an inverter and a divided voltage are input, a comparator for comparing the output voltage and the divided voltage, and a photo-coupler that is turned on and off by an output of the comparator connected to the detection power source via a resistance. The inverter device is capable of detecting on and off of switching elements of an upper arm and a lower arm of an inverter main circuit, that is, an inverter output voltage with approximately the half of a DC input voltage by a high speed.
Further, there is an inverter device described in Japanese Laid-open Patent Publication No. 2006-296008. In the inverter device, a voltage polarity detection circuit consists of a voltage dividing resistance, a resistance connected with the voltage dividing resistance in series, and a comparator for polarity discrimination for detecting polarities of the voltages of the both ends of the series resistance. The inverter device is capable of detecting a residual voltage polarity by the voltage polarity detection circuit between a DC link circuit and a motor line by generating a line potential of an induction motor at the DC link circuit by turning on any one of semiconductor switching elements when the induction motor is in a free run state due to an instantaneous power failure or the like.